The long-term goal of this project is to examine the biochemical, behavioral, endocrinological and toxicological effects of drugs which influence catecholaminergic neurons in the central nervous system. Particular attention will be directed toward the actions of dopaminergic agonists and antagonists on nigrostriatal, mesolimbic and tuberoinfundibular neuronal systems. Projects will involve experiments on: 1. Drug-induced alterations of dopaminergic receptor sensitivity. 2. Control of the anterior pituitary by dopaminergic neurons. 3. Self-administration of direct and indirect acting dopaminergic agonists. BIBLIOGRAPHIC REFERENCES: Mueller, G.P., Simpkins, J., Meites, J. and Moore, K.E.: Differential effect of dopamine agonists and haloperidol on release of prolactin, thyroid stimulating hormone, growth hormone and luteinizing hormone in rats. Neuroendocrinology 20: 121-135, 1976. Gudelsky, G.A., Annunziato, L., Ravitz, A.J., Eikenburg, D.C. and Moore, K.E.: Effects of estrogen on serum prolactin levels and dopamine turnover in nigrostriatal and tuberoinfundibular neurons of the rat. Fed. Proc. 36: 278, 1977 (Abstract).